By the 1940s, the Production code would see some challengers first from the eccentric Hollywood mogul Howard Hughes.
Hughes discovered the voluptuous Jane Russell and gave her her first role 1941’s The Outlaw - Hughes was in love with Russell’s breasts and who wouldn't? Well, not the The Breen Office which requested 37 specific reshoots objecting to the emphasis on Jane Russell’s bosom.
Further troubles with State censorship boards forced Hughes to shelve The Outlaw until the film got a limited distribution in 1943. Mired again in battles over censorship Hughes shelved the project for another few years until he finally got a distribution deal in 1946 with a non MPAA signatory United Artist (The MPAA - Motion Picture Association of America - was the name of the MDDPA after Hays retired in 1945). This started a legal firestorm with the MPAA. Despite, or perhaps because of the PR generated by the court battles, United Artist road showed The Outlaw to bountiful profits everywhere it went.
The power of the code began to crack as the studio system fell out of power the 1950s. Once studios were no longer to permitted to own theaters according to the Supreme Court, movie theaters were freer to show whatever they wanted - and sometimes they showed unapproved foreign films.
This led to the 1952 case of Joseph Burstyn v. Wilson. Dubbed the "Miracle Decision", referring to an Italian Roberto Rossellini short film entitled The Miracle - the Supreme Court reversed its earlier stance ruling that
expression by means of motion pictures is included within the free speech and free press guaranty of the first and Fourteenth Amendments
Though it would take another decade for the production code to completely erode away, the threat of government intervention was now gone.
As the dollar had forced the studios’ hand into the strict binds of the Production code, it was the dollar that would free them.
In 1953 Otto Preminger openly defied the PCA by releasing The Moon is Blue - a romantic comedy which the Breen office objected as having:
...an unacceptably light attitude towards seduction, illicit sex, chastity, and virginity,
The film went on to be a hit without the PCA seal of approval.
Preminger openly defied the PCA again in 1955’s Man with the Golden Arm starring Frank Sinatra playing a heroin addict - yet another hit.
Then Elia Kazan’s Baby Doll released by Warner Bros in 1956 recieved a seal approval but was openly condemned by the League of Decency. It also went on to be a success.
By the 1960s it was a free for all with films like the British made Blow Up with nudity become a box office smash. The Cat was out of the bag and the MPAA began looking to scrap the code in favor of a classification system.